Import latest WritableStream tests from upstream

third_party/WebKit/LayoutTests/http/tests/streams/writable-streams/general.js

 'use strict';
 
 if (self.importScripts) {
   self.importScripts('/resources/testharness.js');
 }
 
 test(() => {
   const ws = new WritableStream({});
   const writer = ws.getWriter();
   writer.releaseLock();
@@ skipping 134 matching lines @@
   return promises.start
       .then(thisValue => assert_equals(thisValue, theSink, 'start should be called as a method'))
       .then(() => promises.write)
       .then(thisValue => assert_equals(thisValue, theSink, 'write should be called as a method'))
       .then(() => promises.close)
       .then(thisValue => assert_equals(thisValue, theSink, 'close should be called as a method'))
       .then(() => promises.abort)
       .then(thisValue => assert_equals(thisValue, theSink, 'abort should be called as a method'));
 }, 'WritableStream should call underlying sink methods as methods');
 
+promise_test(() => {
+  const ws = new WritableStream();
+  const writer1 = ws.getWriter();
+  assert_equals(undefined, writer1.releaseLock(), 'releaseLock() should return undefined');
+  const writer2 = ws.getWriter();
+  assert_equals(undefined, writer1.releaseLock(), 'no-op releaseLock() should return undefined');
+  // Calling releaseLock() on writer1 should not interfere with writer2. If it did, then the ready promise would be
+  // rejected.
+  return writer2.ready;
+}, 'redundant releaseLock() is no-op');
+
 done();